Failure Analysis of Connecting cables Terminal Crimping

July 8, 2024
Posted by admin

Terminal crimping operation is an important process in wire harness processing. In the entire industry, the occurrence of poor processing in this process is relatively high. Only by improving the yield rate of terminal crimping operations can we significantly increase the production capacity of wire harness processing and improve the efficiency and quality of wire harness processing. So what are the reasons for poor crimping terminals in automatic terminal machines?
The following lists the main undesirable phenomena in terminal crimping operations and analyzes the common causes of the undesirable phenomena:
1: Poor terminal distortion and deformation
Manifestations:
1. The phenomenon of lateral bending and deformation of terminals;

Terminal axial distortion and deformation.

The core wire is loose after crimping the terminal

Bad reasons:
1. The terminal is not in the center of the lower blade and is tilted to the left/right;

When the terminal transfer device of the mold transports the terminals to the end position, the spring tension of the transfer device is too weak or too strong. The terminal cannot be transferred to the correct position of the head, and the mold does not reach or exceed the situation;
Failure will occur if the blade (Crimper/Anvil) is worn when punching terminals;

Crimp terminals are tilted & terminal hooks are defective

4. The poor bending of the terminal is caused by the misalignment of the center of the crimper and the lower blade. In addition, it will also cause the blade to wear and make the indentation mark too deep;
5. Defects caused by the terminal not being fed in place due to wear of the position adjustment wire.2: The wire harness is not assembled in place and is defective

There is a gap between the cut surface of the crimp terminal and the flat tip

Manifestations:
1. Deep punching: press the core area to the wire sheath;
Deep drilling: The core wire length is too long, causing terminal deformation;
3. Shallow beating: The outer sheath or core wire is not pressed into the designated area;
Bad reasons:
1. The stripping length of the core wire is too long or too short;
2. The crimping is caused by the incorrect positioning of the wire.

Causes of defective cutouts of crimp terminals

Three: The bell mouth of the terminal is defective
Manifestations:
Bad reasons:
1. The position of the terminal and crimper is wrong and the bell mouth is not formed or is too large;
2. The flat head is further back than the STRIP Guide Plate, and problems may occur when the terminals are shifted and transferred;

The reason why the bell mouth is too large due to terminal crimping

Four: The terminal cutout is defective
Manifestations:

Bad reasons:
1. The defective phenomenon occurs when the cut part of the terminal is not in the correct position, but is more protruding or inward. Poor cutting edges are manifested in cutting edges that are too long or too short, the cutting surface is inclined, scratched, and the cutting surface is curved. When the cutting opening is too long, the box will not be inserted in place and the box will hang. If it is too short, it may damage the terminal;
2. When the terminal is cut, the cutting part will be rough and rough.
reason:
① When the cut surface is worn
② The end of the insulating flat plug is worn
③ If there is a gap between the cut surface and the flat plug

Terminal crimping is tilted to the left-right

Five: Terminals are raised & terminal hooks are defective
Manifestations:
1. Terminal hook refers to the phenomenon that the front end of the terminal bends upward when the terminal is terminated;
2. Terminal tilt refers to the phenomenon that the front end of the terminal bends downward when the terminal is terminated.

Bad reasons:
1. The terminal is not in the correct position of the flat head;
2. The flat head and support platform are not in the correct position;

Terminal axial distortion and deformation phenomenon

Six: Loose core wire defects
Manifestations:
All wire cores are not completely enclosed in the crimping area;
Bad reasons:
During the process of stripping off the insulation layer or bundling the cables, the core wires become loose, which can be improved through process control and the use of half-stripped wires;

The phenomenon of lateral bending and deformation of terminals

Defects in the wiring harness pressing area
Manifestations:
1. The outer knife lock pierces the insulation layer;
2. The outer knife lock does not fully hold the wire;
3. The lock mouth is asymmetrical on both sides;
Bad reasons:
1. The blade does not match;
2. Adjust the crimping height;8: Defects caused by terminal transmission distance (Feeding)
Feeding distance refers to the moving distance from the end to the next terminal slot, as shown in the figure:Manifestation and reasons:
1. Poor transmission caused by the gripper not being in place
2. Poor transmission caused by wear of the gripper;9: Defective terminal pulling force NG
Expression form: After crimping, the pull-out force test is NG (excluding mold factors)
Bad handling method: adjust the crimping height
1. General mold adjustment method for crimping height
2. How to adjust the crimping height of Cam type mold

The above is an introduction to the causes of automatic terminal machine failure and poor crimping terminals. It also summarizes 9 causes and improvement methods of poor terminal crimping. I believe everyone has a certain understanding of the reasons for poor crimping in automatic terminal machines. In daily life, you must do a good job in maintaining the automatic terminal machine to improve the efficiency of crimping terminals and save labor costs.